1. Field of the Invention
The present invention relates to apparatus for pasteurizing or heat treating fluid products for consumption by animals or humans.
2. Description of the Relevant Art
Since the dawn of history, various methods and apparatus have been devised for the heat treatment of foodstuffs for human and animal consumption, including cooking, pasteurization and sterilization. Both pasteurization and sterilization have been used with milk and related products. U.S. Pat. No. 4,310,476 provides in columns 1 to 5 an extensive discussion of pasteurization and sterilization of milk, which is incorporated herein by reference. Column 30 of the same patent identifies legal U.S. standards for milk pasteurization, which are also incorporated by reference.
Dairy farmers and other producers of foodstuffs such as milk are often required to transport their produce to central plants for processing including pasteurization or sterilization and packaging. In less advanced countries, modern processing plants may be unavailable or inaccessible, so that dairy products must be utilized locally, with whatever processing is available. Excess milk may be used on the farm for feeding calves or other livestock, but may spoil or transmit disease if not pasteurized. There is an apparent need for portable, economical apparatus for pasteurizing such milk on site to permit its safe use for feeding calves and the like. There is also a need for portable, simple and economical apparatus for processing milk at or near the source in less advanced countries for both human and animal consumption.
Numerous patents disclose methods and apparatus for sterilizing food enclosed in containers. For example, U.S. Pat. No. 5,424,087 discloses methods of sterilizing canned food in a sterilizing kettle, using hot water for preheating and steam for sterilization.
U.S. Pat. No. 4,739,699 discloses apparatus for pasteurizing or sterilizing edible foodstuffs in containers.
U.S. Pat. No. 2,082,460 discloses apparatus for sterilizing and subsequently cooling food in closed containers, using a form of pressure cooker.
U.S. Pat. No. 5,280,748 discloses apparatus for uniformly cooking packaged foods in a "cook/chill" tank in which hot water is circulated to cook the food, then cold water is circulated to provide rapid cooling.
U.S. Pat. No. 5,080,164 discloses a process and device for heat treatment in continuous flow of a product mixture containing solids in liquid (i.e., a slurry), using a combination of heat exchangers to heat and then cool the slurry.
U.S. Pat. No. 3,780,644 discloses a mobile milk processing system mounted upon a motor vehicle, providing for field pasteurization, homogenization and packaging of raw milk. Water is heated or cooled and circulated as a heating and cooling medium. This system is intended to overcome the disadvantages of central processing plants which process milk in continuous flow.
U.S. Pat. No. 5,209,157 discloses a plant for manufacturing dairy preparations based upon skim milk and vegetable oils. A heater provides for brief heating and cooling of the product prior to packaging.
U.S. Pat. No. 4,534,986 discloses a system for the indirect "ultra-high" heat treatment of liquids such as milk with minimal thermal damage.
U.S. Pat. No. 4,515,823 discloses a process and apparatus for separation of raw milk into cream and skim milk, the latter of which is pasteurized and cooled by regenerative heat exchange in heat exchangers.
U.S. Pat. No. 4,446,781 discloses a process and apparatus for mechanical/thermal treatment of fluids such as melted cocoa masses, which can include sterilization and pasteurization.
U.S. Pat. No. 5,360,055 discloses a method and apparatus for heat treating fluid products such as milk, including a counter current heat exchanger.
U.S. Pat. No. 5,443,857 discloses a method and apparatus for sterilizing milk based liquid products, including indirect preheating and final heating to sterilization temperature by direct steam injection, followed by flash-cooling.
U.S. Pat. No. 3,973,048 discloses a method and apparatus for sterilizing liquids by brief heating, involving compression and pressure reduction to transfer heat and attain sterilization temperatures.
U.S. Pat. No. 4,738,302 discloses apparatus for heat-treating liquid products including series-connected multi-tube heat exchangers for heating and cooling the products.
U.S. Pat. No. 4,432,276 discloses apparatus for heating, pasteurizing and sterilizing fluid foodstuffs in which the substance to be heated is brought in direct contact with a heating fluid.
U.S. Pat. No. 4,446,778 discloses a pasteurization system for dairy farming products, including several basins wherein the pasteurization cycle is effected in sequence, the heat taken from one basin during its cooling phase being used to heat at least one other basin. A refrigerating circuit, heat pump and heat exchanger are used to heat and cool the basins.
U.S. Pat. No. 4,310,476 discloses apparatus for treating fluids at sterilization temperatures in which the fluid is heated by direct contact with steam while it is in the form of a thin, free-falling film or stream.
Most of these patents disclose apparatus and methods for the continuous processing of milk or other foodstuffs, and most of these systems are complicated and expensive. There remains a need for a simple, economical portable apparatus for batch processing of milk on dairy farms and the like.